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We show how to interoperate, semantically and inferentially, between the leading Semantic Web approaches to rules (RuleML Logic Programs) and ontologies (OWL/DAML+OIL Description Logic) via analyzing their expressive intersection. To do so, we define a new intermediate knowledge representation (KR) contained within this intersection: Description Logic(More)
B ecause we can process only a tiny fraction of information available on the Web, we must turn to machines for help in processing and analyzing its contents. With current technology, machines cannot understand and interpret the meaning of the information in natural-language form, which is how most Web information is represented today. We need a Semantic Web(More)
semantic interoperability on the Web, but XML addresses only document structure. RDF better facilitates interoperation because it provides a data model that can be extended to address sophisticated ontology representation techniques. T he World Wide Web is possible because a set of widely established standards guarantees interoperability at various levels.(More)
Metadata for the World Wide Web is important, but metadata for Peer-to-Peer (P2P) networks is absolutely crucial. In this paper we discuss the open source project Edutella which builds upon metadata standards defined for the WWW and aims to provide an RDF-based metadata infrastructure for P2P applications, building on the recently announced JXTA Framework.(More)
The World Wide Web (WWW) can be viewed as the largest multime-dia database that has ever existed. However, its support for query answering and automated inference is very limited. Metadata and domain speciic ontologies were proposed by several authors to solve this problem. We developed Ontobroker which uses formal ontologies to extract, reason, and(More)
Recently, a widespread interest has emerged in using ontologies on the Web. RDF Schema (RDFS) is a basic tool that enables users to define vocabulary, structure and constraints for expressing metadata about Web resources. However, it includes no provisions for formal semantics, and its expressivity is not sufficient for full-fledged ontological modeling and(More)
Large volumes of content (bookmarks, reviews, videos, etc.) are currently being created on the " Social Web " , i.e. on Web 2.0 community sites, and this content is being annotated and commented upon. The ability to view an individual's entire contribution to the Social Web would be an interesting and valuable service, particularly important as social(More)
Online community sites have replaced the traditional means of keeping a community informed via libraries and publishing. At present, online communities are islands that are not interlinked. We describe different types of online communities and tools that are currently used to build and support such communities. Ontologies and Semantic Web technologies offer(More)
Storing and querying resource description framework (RDF) data is one of the basic tasks within any semantic Web application. A number of storage systems provide assistance for this task. However, current RDF database systems do not use optimized indexes, which results in a poor performance behavior for querying RDF. In this paper we describe optimized(More)
The World Wide Web (WWW) is currently one of the most important electronic information sources. However, its query interfaces and the provided reasoning services are rather limited. Ontobroker consists of a number of languages and tools that enhance query access and inference service of the WWW. The technique is based on the use of ontologies. Ontologies(More)